Synonyms and other taxonomic changes
Bibio vestitus Walker, 1848
Bibio nervosus Loew 1864
Bibio basalis Loew
Bibio mickeli Hardy, 1937
is a boreomontane species occurring at far northern latitudes and usually in montane regions at more southern latitudes. The flight period of Arizona populations is June, which corresponds to the June through July flight period of populations elsewhere."(1)
Leg color can vary from black to almost entirely red. Males normally have dark femora, females red femora.
Mostly red-legged females are similar to B. xanthopus, which usually has shorter spurs and always(?) has more antenna segments. See discussion here:
Females with only femora red can be confused with B. femoratus, which has all coxae and trochanters black (red in vestitus).